The invention concerns the sheet metal wheels of commercial vehicles equipped with valves for the inflation of tires, particularly those equipped with circumferential groove mounting rims and the valve of which emerges outside the wheel disk.
An example of a wheel of this type is described in patent EP 0 701 911 B1. That wheel comprises a disk and a rim with an outer hook, an outer seat, a safety element, a first connecting area where a valve hole is placed, a second roughly cylindrical connecting area, a circumferential mounting groove with an outer flange and an inner flange, an inner seat and an inner hook, the connection between the disk and the rim being made in the second connecting area, the diameter of which is greater than that of the mounting groove, in which the safety element consists of a circumferential boss or xe2x80x9chumpxe2x80x9d.
That wheel has the advantage of having a valve which does not enter the inner space of the wheel disk. It does, however, entail difficulties with mountings and demountings of the tires it is intended to receive.
On mounting of a tire, after having introduced the two beads in the mounting groove, the outer bead of the tire must pass over the hump in order to reach its position on the outer seat. By reason of the large diameter of the hump, that passage must take place in several successive stages. The tire bead is first passed over the hump area close to the valve. Then the tire is inflated and the internal pressure ensures complete passage of the bead over the hump and it is set in place on the outer seat. That application of pressure from the internal cavity of the tire is not possible when the outer bead has not crossed the valve base. It is therefore necessary to define a particular operating procedure for those wheels.
Crossing of the hump in several stages can also be the cause of an irregular placement of the outer bead on the outer rim seat, which can cause a rolling unbalance.
On demounting of the tires, it is also necessary to observe a particular operating procedure with specific tools in order to be able to pass the outer bead of the tire without risk of damaging it through excessive stresses, notably, on crossing of the valve area.
Those problems are very significantly improved by the wheel according to the invention.
The term xe2x80x9ccommercial vehicle wheelxe2x80x9d herein is understood to mean a wheel of diameter greater than or equal to 17.5 inches (444.5 mm). xe2x80x9cAxial directionxe2x80x9d means a direction parallel to the axis of rotation of the wheel.
The wheel according to the invention comprises:
a disk, and
a rim with an outer hook, an outer seat, a safety element, a first connecting area in which a valve hole is placed, a second connecting area, a circumferential mounting groove with an outer flange and an inner flange, an inner seat and an inner hook, the connection between said disk and said rim being made in said second connecting area, the diameter of which is greater than that of said mounting groove.
That wheel is characterized in that the safety element consists of a cylindrical wall or ledge of diameter identical to that of the inner end of the outer seat and in that, "PHgr" being the diameter of the wheel and p the axial length of the cylindrical wall,
10xe2x89xa6p/"PHgr"xc3x971000xe2x89xa635
According to an advantageous embodiment:
12xe2x89xa6p/"PHgr"xc3x971000xe2x89xa626
According to another characteristic, xc3x8 being the diameter of the radially outer wall of the ledge, the result is:
xc3x8/"PHgr"xe2x89xa70.96
It is, in fact, preferable, in order to maintain the unseating prevention performance of the safety elements of the wheels according to the invention, to have the diameter of the radially outer wall of the ledge as close as possible to the diameter "PHgr" of the wheel.
The wheels according to the invention preferably have a width greater than or equal to 5.25 inches (133.5 mm).
That wheel has the advantage of presenting a device to prevent unseating of the outer bead of the tire, called a ledge, as efficient as the hump of the previous wheel, in spite of its very short axial length. That ledge also affords this wheel a notable advantage on mounting of a tire, because the outer bead can easily cross that ledge in a single operation. That also facilitates good placement of the bead on the outer seat. Finally, on demounting, it is observed that the stresses necessary to separate the beads from the seats and to make them drop into the mounting groove are very notably reduced. That makes it possible to reduce the risk of damage to the tire. Finally, on a manual demounting, it is not necessary to use a specific tool, in contrast to the wheels corresponding to EP 0 701 911 B1.
An embodiment of the invention is now described nonlimitatively with the aid of the following attached drawings.